Two-Carbon Homologation of Aldehydes: An Efficient Route to Difluoromethyl Alkynes

Abstract We report a simple and efficient two-carbon homologation method to directly convert aldehydes into difluoromethyl alkynes by using readily accessible and stable diphenyl(2,2,2-trifluoroethyl)phosphine oxide [Ph2P(=O)CH2CF3]. The conditions for this reaction are compatible with a broad range of aldehydes. Deuterium-labeling experiments suggest that the reaction probably involves a key rearrangement of aryl difluoroallenes generated in situ.